Shears



Feb. 13, 1923.

A. KARCZEWSKI SHEARS Filed Dec. 12, 1921 I vvvvis 7/7/1 Patented Feb. 1? 1923.

ALPHONS KABCZEWSKI, OF CLINTONVILLE, WISCQNSIN.

Application filed December 12,1321. Serial No. 521,734.

T 0 all whom it may concern.

Be it known that l, ALrrioNs Kanoznwsiri, a citizen of the United States, and resident of Clintonville, in the county of YVaupaca and State of Wisconsin, have invented certain new and useful Improvements in force is on a vertical line running through the middle of the knife edge. This does away with any tendency of the knife to wabble or engage frictionally with the guides in which it slides.

An important object of the structure is the provision of such a combination of parts that there will be less resultant wear on contacting surfaces induced by long usage.

A further object is the provision of a portable structure.

A primary advantage lies also in the means whereby the length of the cuts in pieces of metal is readily determined and adjusted so that the metal need only be inserted in the shears and the desired length of cut results from a given movement of the handle.

Other objects and advantages will appear as the description proceeds.

Reference is had to the accompanying drawings, in which Figure 1 is a. side elevation with a side plate removed.

Figure 2 is a cross section on the line 22 of Figure 1.

Figure 3 is a side elevation, and

Figure 4 is a cross sectional detail of the shaft and associated parts.

Base 10 has secured to it by bolts 11. side plates 12 apertured to receive shaft 13. A shear 14 is secured to base 10 by screws 15. Handle 16 rotates freely onshaft 13 being secured from removal by washer 17 secured by screw 18 threaded in shaft 13. A key 19 is rigid with the shaft and received in slots in lever arm 20 which is provided with teeth 21. Handle 16 has a detent 22 threaded through an opening in a shoulder 23 formed by a deformation of the handle. Detent 22 is pressed downwardly by spring 24 actuating upon collar 25 rigid with the detent. The detent also extends through an aperture in a lug 26 projecting laterally above the shoulder of the handle, and limiting the downward movement of the detent by contact with a deformation 28 of detent 22.

' Circular disk 29 is secured to lever arm 20 by screw 30 which prevents travel of lever arm 20 along shaft 13. Eccentric 31 contacts with circular disk 29 so that movement of lever arm 20 results in rotation of eccentric 31 with shaft 13. 'A cam 32 surrounds eccentric 31 which is free to rotate therein, and has a finger 33, integral therewith. Shear 34 is secured by screws 35 to plate 36, one of whose edges contacts with base 10 and the other of which is contiguous with bar so'that plate 36 is free to move only in a vertical direction and is provided with a guideway. I

0n movement of lever arm 20, eccentric 31 is rotated to the right, looking at Figure 1, and by means of finger 33 urges shear 34 downwardly. The point of application of finger 33, it will be noted, is in a vertical line bi-secting the edge of shear 34. The extreme movement of cam 32 to the right is limited by the dimensions of opening 38.

It will be noted that there is little wear of parts by reason of the rotation of eccentric 31 in cam 32. I

It is obvious that the downward movement of shear 34 is limited by the amount of rotation of lever arm 20. When, therefore, the degree of rotation of the lever arm is altered, there will be a resultant variation in the length of the. cut made on the piece of metal held against shear 14. Hence the provision of teeth 21 and detent 22. Figures 1 and 3 define an extreme limit of movement of handle 16-when detent 22 is centrally positioned with respect to the four teeth 21. If detent 22 is positioned between any other pair of teeth, the limit of motion of arm 16 remains the same but the downward travel of shear 34 is altered, because a greater or lesser rotation of lever arm 20 on shaft 13 results. Consequently the cut made in a piece of material of given thickness inserted at the extreme forward point between shears 34 and 14, will be varied. Hence the provision of teeth 21 is useful for getting cuts of various length.

lVhen the topmost portion of eccentric 31, as shown in Figure 1, has been lowered, it moves downwardly at a more rapid rate than it does when moving in the position shown in Figure 1. This, however, does not operate to decrease the force exerted through handle 16 on the piece being sheared, because as cam 32 nears its right hand position, its finger 33 travels upwardly with respect to the horizontal plane in which the center of the eccentric lies.- Hence the shear is capable of exerting powerful force even when the handle 16 nears the limit of position shown in Figure 3.

It will be noted that the described structure, while adapted to give great strength, is comparatively light and adapted for portability, a handle 39 being secured by bolts 1'! for this purpose.

With certain heavy pieces ot metal, an un desirable distortion results from the shearing action and a screwetl) is consequently provided, threaded in lug 4:1, integral with plate 12 and which is adjustable and holds the plate in horizontal position when it is being out.

While a preferred embodiment of the invention has been illustrated and described, it is to be understood that the present invention is not confined to such specific embodiment, but may be otherwise embodied within the spirit of the invention and the scope f the following claims, and it will further be understood that a substantial range of equivalence is contemplated.

I claim:

1. The combination of a support having guide surfaces, a plate slidable on said surfaces, a knife supported on said plate, said plate having an opening therein, a cam positioned in said opening and provided with a finger, said cam having a circular opening therein and an eccentric movable in said opening.

2. The combination of a support having;- a guideway therein, a plate slidable in said guideway', a knife carried by said plate, said plate having an opening therein, a cam in said opening, an eccentric in said cam, a shaft rigid with said eccentric, said support having an aperture receiving said shaft, a

lever arm rigid with said shaft, a second lever arm rotatable on said shaft, and means for adjustably securing said second lever arm with respect to said first mentioned lever arm.

In testimony that I claim the foregoing I have hereunto set my hand at Clintonville, in the county of Waupacaand State of Wisconsin.

ALPHONS KARCZEWSKI. 

